Platforms

The Gen2 SDS Platform follows the Gen1S Platform, building on a single evolving frame design around a compartment sized for a full battery power pack (the Monolith), but also featuring a 3-Brick battery or a Longbrick battery for lower entry-cost models.

Frame/Bodywork

Frame

The 2013+ Zero frame for S/DS/SR/DSR bikes is made of anodized aluminum, weighs 23lbs, and is a combination of cast parts and welded square tubing of 1-inch outer width.

The frame slips onto the battery pack case over the top and attaches to it with four major bolts around the bottom. The charger is attached to the underside with a protective plate covering it (plastic for S/SR, aluminum for DS/DSR).

Attachment Points

The frame offers a number of rivet nut attachment points for the lower plastics.

The rivet nuts are sized to accept M5 bolts (a total depth of 20mm is available without marring the inside of the frame bar) with a 6mm shoulder to a depth of 5mm. (A longer shoulder and length are required for fastening a bracket beyond that.)

From 2015 onwards, the frame has extra attachment points made for the crash bars used for fleet/police models.

Two extra rivet nut holes on each side of the frame diagonal shoulder of the same size. They are 30mm apart (center to center).

The lower bash plate has similar modifications from that year - two rivet nut holes pre-made for M6 bolts and capped by threaded plastic inserts on each side for the lower mount. There is perhaps 10mm thread depth or allowance between the outer surface of the plate and the onboard charger enclosure.

The rubber boot covering the Accessory Charging Port is attached to the flange via plastic push-rivet.

One cable run is zip-tied to a slot in the lower left corner of the plate, accessible under the frame arms forward of the onboard charging plug.

Another cable run is zip-tied a slot in the lower edge of the plate closer to the right side, accessible under the frame arms behind the battery.

Mounting

The bracket has side flanges that affix the plate to the left and right sides of the frame.

The top two corners of the flanges bend to the rear of the bike at a 45 degree angle, which mate to similarly-positioned flanges on the frame sides. The frame side flanges are above the plate flanges, which means when installing and removing the plate, the top must be angled towards the rear of the bike.

The bottom two corners of the flanges bend to the rear of the bike at a 90 degree angle. The bolts which affix these corners point upwards (cap head points down).

Tail Subassembly

On the SDS Platform models, there is a separate aluminum assembly supporting the tail plastics, tail extension for the license plate, and the top rack accessory that bolts into the "horns" at the aft end of the frame just after the Sevcon controller.

The FX/FXS seat is closer to an offroad "plank" seat, allowing the rider to pick their position forward or back.

2013 and 2018 FX seats

2013 FX seat

2018 FX seat

Variants

2010-2013 X seat

This seat offers additional height and free movement front to back.

"The 2013 seat is also known as the off-road seat. p/n 24-01596 - SEAT ROODIN RD-M1231-K BLACK. Taller riders tend to like it as well if their butts hit the bump of the contoured seat." per comment on Facebook

2014-current X seat

Has a cutout / dip.

Tapers more at the back (pointy), and flows down the sides a bit more too. Basically it's more contoured to the bike.

Corbin made a low seat for 2010-2012 X platform models.

Mounting

M8×25 bolts are listed as the bolts that run through the tail subframe to the bracket at the rear of the seat to hold it in place.

All variants of the tank plastics for have identical side pieces and a black centerpiece in soft plastic with a relatively rough finish.

The stock centerpiece for 2013-2016 models is a bin container with two drain holes for collected moisture, with a soft bin held together with a simple zipper that anchors via hook-and-loop patches at the bottom of the bin as well as a loop cord that hooks through the front helmet lock.

The bin delivered per model year is different and varies in quality. 2013 seemed to have better construction than 2014-2015 years, and 2016 is somewhere between.

As of 2017, the stock centerpiece is a locking storage container with a spring-loaded hinge at the front so it swings forward to open.

The Power Tank and Charge Tank have tank plastic options which can be bought separately or selected for color customization. Both use a relatively flat surface for the centerpiece, and the Charge Tank has a cutout for a J1772 inlet hold with built in waterproof cover with a spring-loaded hinge.

2014 SP plastics - dewelding

Separating

The join between the centerpiece and side pieces of a Zero tank plastic assembly is made by plastic weld using a soldering iron into soft hollow plastic pins on the centerpiece that melt and flatten around a lock washer onto holes in the side pieces.

You can break these welds using a relatively careful use of a pair of pliers to basically grip hard and twist on them until they break.

It's a slightly frustrating process but pretty quick to achieve, in about an hour. A soldering iron or extremely narrowly-focused heat gun can help the process but try not to risk damaging the plastics from overheating.

The original join process can be repeated for the new centerpiece.

Also, this means that the plastic centerpiece you remove will not be re-joinable.

IKON 3610-ZERO-S Shock Absorber [5] - The spring is too wide at the top, and to be installed, the sping must be compressed. When Installation is complete, the spring is always compressed by at least a couple centimeters.

Wilbers Shock absorber Type 640 Road Part. No.: 640-1143-00 [6] Wilbers claims the shock fits "2011-2013 S M5" (which does not exist). The M5 designation is buried in the VIN of the 2014 S; and may or may not be relevant. This shock could be mislabeled for the DS. Make sure to get full dimensions before ordering.

Yes - DO NOT BUY

ZXTDR Rear Shock Absorber Suspension Sensa-Trac Load Adjusting for Dirt Pit Bike Motorcycle 1200LBS. [7] This shock phyisically fits, but underperforms. It feels like you're riding on a trampoline. You get what you pay for.

Zero uses a belt for primary transmission of torque to the rear wheel. It's quiet and lightweight but is a proprietary design that can wear out. If you plan to put a lot of miles on a Zero or risk the belt often, buy a spare belt ahead of time and mind its maintenance.

Place the gauge in the center of the belt span, such that it is aligned longitudinally with the belt length.

Place a finger on the blue pressure pad and depress this pressure pad.

Keep pressing the blue pressure pad until you feel and hear a distinct 'click'. When this 'click' sound is heard, do not press any further.

Remove the gauge and read the belt tension by observing the point where the top side of the blue indicator arm crosses the numbered scale on the gauge body.

Care must be taken to ensure that the gauge is not 'rocked' when pressing down on the blue pressure pad. The strap above the pressure bar is provided to attach snugly over the finger and prevent any 'rocking' motion.

Due to the fact that this device requires some amount of practice and operator skill, the accuracy and repeatability of the tension readings are not high.

Basically, if you are doing this to try to get more acceleration by moving from a 28 tooth to a 25 tooth, Harlan recommends trading in the DS on a 2015+ SR or 2016 DSR if you need the off road capabilities. You will get much much more acceleration and not hurt your top end performance.

On the drive belt side, the upper rear 5mm bolt takes extreme care to remove. It is tapered to locate the motor. There is a very strong chance of stripping the head and have to drill it out. Make sure to have a machine shop close by just in case.

On the other hand, removal of the motor may not be necessary.

The other 7 bolts, 3 on the sprocket side and 4 on the rear brake side are the only thing simple and straight forward.

You will need a special 3" or longer 6mm allen head socket for sticking in the hole through the frame at the front of the motor.

Remove the rear brake pedal and assembly to get the heel guard out of the way of the top right rear motor bolt.

Be careful not to strip these bolts either.

They have Loctite; use a torch.

And make sure your local hardware store has these replacement bolts handy in case you have to drill them out.

The rear brake pedal needs to move anyway to get the right swingarm bolt out.

Also the sprocket bolt itself, as well as removing and installing the new sprocket on the shaft can be very difficult. Some of the best professionals have had trouble.

Loctite has been used on everything and you will need a torch to remove them.

Even so, you will need a strap wrench with an old belt as the strap to hold the sprocket and a high power impact wrench.

Even with all that right, you have a chance of stripping or breaking the bolt. The sprocket is pressed pretty tight.

Be very careful not to permanently damage the motor bearings by prying between the motor itself and the sprocket to try to remove it, and also by tapping with a hammer to try to fit the new one on. You will be tempted to do both, but you need to find another way.

A gear puller would be much better.

There are other things to watch for:

Mark your phase leads and pay special attention to the routing.

Don't over-tighten the motor jack nuts and bolts until you have the swingarm back in place as it can pull the frame together slightly making it impossible to get the swingarm in place.

Make sure you unplug the 8 way motor encoder harness and it doesn't get yanked and pull a wire.

The top shock mounting bolt is a 15 and 17 mm and can be done with ratchet wrenches 1/32 of a turn at a time, or without ratchet wrenches if you are known to have extreme patience. It can take a while. The 2014 is a little easier and is (seems to be a) dual 17mm bolt and nut.

The swingarm bolts are 10mm allen head and can be extremely hard to relocate even when working with someone else, a rubber hammer, and a flashlight. Those who have replaced their own belt before can vouch for this.

Again, I doubt too many on this forum have done this, and those who did I'll bet agree with me that it makes more sense after they did it and perhaps had their bike out of commission to work through the things that didn't go right, and would agree to just upgrade to the SR or DSR first vs trying to change the front sprocket.

Also the 25 tooth sprocket will break belts easier as less teeth are engaged than the 28 tooth, which can make it more likely to sheer teeth in the event of a wheelspin, and it bends the belt at a sharper radius which can possibly fatigue the carbon strands more. The SR actually uses a 30 tooth front sprocket which is even nicer to the belt than the 28 tooth.

Brake squeal (pad back resonating against caliper cylinder) can be very loud and annoying. Squeal does not technically impact performance but it's very unpleasant and might cause the rider to hesitate before fully braking which is a safety issue.

Solutions

Clean the pads and/or discs for squeaking.

Try a different brake pad (attractive if you want a different pad feel or performance in the first place).

Powertrain

The powertrain includes all of Zero's power storage and delivery components including the battery, but this section focuses on the motor, power delivery via the controller, and their inputs via throttle and drive mode configurations.

Licensing

For a time, Zero openly offered powertrain components in a licensed manner for prototyping and other uses.

Currently, probably for reasons of liability and support overhead, this is not publicly offered but does seem available on request for companies wanting to develop products where Zero's powertrain is a good fit.

Many riders make their own Custom mode settings. There are many options that all involve tradeoffs.

0% (-20%) Max Regen

This enables a "coasting" mode which is very efficient, in allowing the rider to let the bike's momentum carry it forward for a while.

This also helps transition the bike from accelerating to decelerating, since the regen levels come on in a step-wise fashion, which minimizes the dive on the suspension by providing an intermediate step.

NOTE: This has one disadvantage at 0%: in extremely low traction scenarios, this can lead to dangerous fishtailing where the rear wheel starts to slip, in that it can be very difficult to slow it down.

100% Max Brake Regen

Most riders seem to leave this setting at 100% in order to get the most out of their rear brake.

Lower Top Speed (60 or 70mph, say)

This creates a "poor man's" cruise control, where the throttle has no effect at the top end, only ensuring that a specific speed is met.

This can be useful when trying to get a maximum or ensured amount of range.

Lower Max Torque (30% or less)

This can be useful in wet or reduced traction conditions.

Torque setting is mostly about the torque ramp rate (how much torque achieved with a given amount of throttle twist).

By reducing the ramp rate, the onset of a loss of traction is much easier to control and recover from.

Most riders just switch to Eco mode in the rain, but using Custom mode for this can also be effective.

The field must apply synchronously to the rotor, so the calibration between the position sensor and the controller is critical for efficiency, minimizing wear on the bearings, and minimizing heating of the windings and magnets.

The ME1507 is an Radial Air Gap, Permanent Magnet Synchronous Motor (PMSM) with an Internal Permanent Magnet Rotor (IPM). Designed for battery pack voltages of 100 VDC or less. Maximum rotor speed of 6000 rpm. Continuous current of 200 amps, and continuous power of 17 kw. Weight of 44 pounds.

Motor theory

IPM vs SPM for a different motor control regime but some principles translate to the Z-Force motor.

The FST Platform/Gen3 uses the 75-10 variant, which has a new construction in addition to being wider.

Cooling ridges run along the circumference of the cylinder rather than axially parallel to the shaft.

These ridges align with directional airflow from under the frame where the motor controller enclosure guides it.

The construction therefore is no longer an extrusion as in previous casings.

Possibly there are lathe-like methods involved in machining.

The finish in the first model with the motor is bronze, probably indicating something about an alloy change.

-10 suffix indicates 10cm length.

Features

The motor encoder position sensor is now housed in a servicing-accessible enclosure, opposite the shaft, on the right side.

The motor mounts are now more structural, joining the swingarm to the rear of the main frame.

TODO review for a better structural description.

Notes

There was a comment about lamination improvements inside the motor for better heat transfer which will probably get a cutaway illustration soon.

The team were also proud of designing the new motor; it seems to be fabricated in a relatively distinct way, perhaps even unique.

They regretted that their existing extrusion method went by the wayside, because they relished being able to "just lengthen the motor" to get different performance levels out of it, and the new motor design does not afford that in the manufacturing implementation.

You can built a little chair (width of the plate, you put it on the cooling wings) with an M10 tensioner.

Then you bolt an M10 eye-bolt on the pulley so you can pull on the shaft really hard (about 200lbs), and the rotor will pull out on the shaft along with the drive plate and bearings.

Warning:

Once you have the shaft and rotor out, be careful as it is highly magnetic and you can get your fingers pinched quite easily on it.

At that point, I found that the rotor is loose on the shaft.

You have to remove the rear bearing, remove the c-clip holding the rotor laminations on the shaft, use a marker or something to mark the front and back of the rotor and how it is aligned on the shaft because you are going to take it off.

Warning:

It is important that it goes on in the exact same direction, otherwise the motor could spin backwards.

Once you have the rotor and the shaft labeled so you can get them back together exactly the same way, slide the rotor laminations off the shaft.

Clean the shaft and the inside of the laminations.

Apply a lot of loctite 648 on the shaft and lamniations, then slide them back together.

Ensure that they go together the same way that they were before, and that the loctite 648 gets well-distributed between the shaft and the laminations to make a solid bond.

Put the c-clip back on, put the bearing back on (or put a new bearing on since removing a bearing without damaging it is quite hard, the front and rear bearings are both 6006-2RS).

When you put the new bearing on, make sure you just push on the inner race for the press fit, if you push on the outer race it will transfer the force through the balls and likely damage them.

The bearing should be a press fit, if it slips on or off easily, you should glue it on with the loctite 648.

Let the 648 cure for a few hours before putting the motor back together.

To put the motor back together, just do the same thing you did to pull it apart, but opposite.

Ensure that the wave-spring is still in the bottom of the bearing pocket at the bottom of the motor.

Warning:

Be careful to not let the rotor slam back into place, that could damage the bearing

Make sure you control the rotor: use the little chair and unscrew the tensioner to let the magnetic forces pull it back in slowly.

Once it is almost all the way in, the bearing will catch on the bearing pocket.

At that point, it might take a little jiggling around and some force on the end of the shaft to get it to pop into place, then it could take a bit more force to get the drive-plate to re-engage with the stator case.

The following regards what engineering constraints limit the power and RPM of the (IPM) Z-Force motor. Pre-IPM motors generated more heat for a given amount of power, so cooling was usually the first concern, but the IPM design pushes the frontier further so the topic is worth addressing.

RPM

The Z-Force motor is design-limited to 6,000 RPM as follows.

RPM is primarily limited by the inductance of the motor windings.

At low RPM, under full throttle, the current through the driven phase(s) of the motor ramps up from 0 to the maximum allowed by the controller pretty quickly, and you get full torque because you've got full current.

But the faster the motor turns, the faster the motor controller has to cycle the phases of the motor on and off, and eventually, you reach a point where there's not enough time (because of the inductance of the motor windings) for the current to ramp up to maximum before that phase has to be turned off and the next phase cycled on.

At that point, power starts to drop off, so very shortly after that, the motor won't have enough torque or power left to drive the load.

The mechanics of the motor could easily have been designed for higher RPM, but there's no point since you'll be current-limited anyhow.

Torque / Power

The easiest way to get more torque, and thereby more power (since power is proportional to torque times RPM), is to pump more current through the motor.

Several things can bottleneck that effort:

First, the motor windings have a DC resistance because they're copper wires with fixed gauges and lengths.

The bike's wiring external to the motor also has some DC resistance in it.

If you apply more voltage to a fixed DC resistance, you'll get more current, but the batteries only give you ~110VDC to play with....and of course, the battery has a current limit of its own.

You'll need to be sure the controller can handle the current as well; you won't go very fast once you smoke the controller.

Since the motor rotates and therefore the windings have to be commutated (driven on and off in the proper sequence and speed), the motor's inductance also comes into play as discussed above about RPM.

You could change some of this stuff fairly easily (higher-gauge wiring is pretty simple, though might be tough to fit in some of the tight confines the Zero's wiring is routed through), but other things are more difficult.

To reduce the motor winding's DC resistance, you'd want to use heavier wire, but you wouldn't be able to get as many turns onto the same coil form.

Fewer turns would create less inductance, which also helps allow higher current levels, but fewer turns also results in a weaker magnetic field for the same current, so you might actually reduce the torque the motor puts out.

Then you'd also need to be sure you don't over-current the controller, or the batteries, and cooling everything involved becomes an additional topic.

It's kind of like asking what's the highest VO2 max an athlete can put out.

It's not just about his lungs, it's about his heart, his muscles, his metabolism at a microscopic level, even about his mental attitude.

Tweak any one thing and the system's whole balance shifts.

That's why engineers make the medium-sized bucks!

Speed

Vehicle top speed can only be altered by the gearing (sprocket ratios).

Power output is not affected by gearing; only torque is.

So, a ratio yielding a higher top speed will result in lower torques throughout the range, resulting in slower accelerations from start.

This exposes high-voltage terminals that can damage tools, equipment, or cause injury or death if not de-energized.
Ensure the bike is fully de-energized or that you are using professional methods and safety precautions.

The control mode translates the throttle signal into motor operation, so it makes the throttle target a speed or a level of torque.

Dual throttle inputs.

Regen proportional to the throttle.

Directional throttle.

Speed limit proportional to throttle.

Reverse speed limit.

Regen

The Sevcon controller manual refers to regen as braking, and has a number of recommendations and features disabled to help prevent wheel lockup for "on-highway applications".

Braking

The Sevcon can also apply reverse torque as braking or a reverse gear, and supports separate speed and torque limits while the motor is rotating in reverse, very important if used on a Zero since motorcycles are unstable when reversed so must operate within human walking speeds.

Some MBB settings direct the Sevcon controller; look to the MBB first.

The MBB can also provide a dump of Sevcon diagnostics and logs.

DVT software to maintain the Sevcon programming is available but recent versions require a license and the cabling is not cheap. The older unlicensed versions may have trouble maintaining newer programming by Zero.

This exposes high-voltage terminals that can damage tools, equipment, or cause injury or death if not de-energized.
Ensure the bike is fully de-energized or that you are using professional methods and safety precautions.

It's relatively effective to treat each increment as representing 9% of charge state, and do a little mental math to figure out that each increment could represent 6-12 miles (for say 2013), and work out the remaining range / speed tradeoff from that.

go slower to get closer to 12 miles of range per increment

go faster if you can afford to burn off the battery to reach your destination in time.

This instrument cluster has two M6 (6mm diameter) threaded rods extending from the rear of the enclosure, captured against the plastic shoulder pieces to the headlamp assembly by two 10mm nylon locknuts.

Remove the display before removing the plastic shoulder pieces, and re-intall the plastic shoulder pieces before re-installing the instrument cluster.

Common Problems

Clock skew

The internal clock is separate from the MBB clock so can drift over time, often faster by minutes per month or so.

Loss of indication

When these have issues, it has mostly been due to moisture entering the (relatively well-sealed) housing.

This can be disassembled for cleaning but would need re-potting with dielectric grease perhaps when re-assembling and need to be very clean and try inside.

Loss of Clock

When the clock reads 00:00 and will not respond to adjustments, it is likely that its internal battery has failed.

Confirm by observing the indications on startup. If "EEE" appears in the main speedometer readout, the battery is likely dead.

Moisture Ingress

The instrument cluster's operation depends entirely on being perfectly sealed.

The Calex / GreenWattPower EVC-116-1300 and EVC-116-720 are used as onboard chargers for modern Zero models (2014 onwards except for the 2014FX) and are CANBus-controllable which eliminates the CCU board.

Calex connections uncovered

Calex connections

Design

The board is a solid-state switching power supply with a CAN interface.

The charger attempts to deliver a target amount of current to the battery.

This means that the charger's power input is proportional to the battery's voltage at that moment, which rises from low state to the high state of charge, so charging will be slower at low voltages (< 20% SoC).

When the onboard charger is plugged in and powered on the onboard charger pushes:

5V and 48mA through the Charger attached Pin #11.

5V and 26mA through the Charger enabled Pin #12.

The 5V ground reference is Pin #13 which is battery negative.

With this knowledge, another onboard charger solution can be wired to function as follows:

Run a separate circuit that when triggered pushes 5V ~50mA through pin#11 (attached charger) with the other end of the 5V circuit connected to the battery negative pin #13.

When this is triggered, the bike shows the battery state of charge % and charge time remaining, closes the contactor and allows charging - through the accessory charging port, the onboard charger port or via the Sevcon battery terminals for high power charging.

Upon completion of charging, the 5V can be switched off and the charge level and time remaining switch off and the contactor opens just as with the onboard charger.

The bike can be keyed on and ridden away as normal.

Using this method there is no need to leave the bike on when charging via the accessory charging port or the controller battery-side cables, or if you are using the accessory charging port without triggering the auxiliary pin on the accessory charging port's Anderson SBS75XBRN.

NOTE

For 2015 onwards, the charger install uses additional wiring which may have a different approach using CAN signals, so it may require a different approach.

Unbolt the belly pan (2 rows of 4 3mm Allen head bolts on each side of the pan, and 2 smaller bolts) and remove it.

Unplug the wiring at the rear of the charger area.

There are three plugs (looking left to right at the rear of the charger):

One on the AC end of things that's bolted to the bike (your charge plug)

The comms connector (enable signal, CAN comms etc...)

One plug on the DC side that goes up to the charge wiring harness.

The comms plug just has a tab; push in the tab and pull that one out.

Both of the other plugs are really difficult.

Removing the DC plug.

The plug is an AndersonSBS50-BRN, but it seems to be a narrower pin pitch with no center data pin set.

The DC plug is located in front of the motor against the back side of the battery on the bike's right.

The cables are tucked up between the battery and a frame member, so cut the zip ties (including the zip tie holding the plugs together) and pull the plastic zip-tie mount clips on the lower half of the cable going to the charger.

Pull down on the charger side of the connector from the bottom while pulling up on the top connector.

Sometimes this requires a "flesh donation" to the motor, so covering the motor with a rag would be smart.

Pull the terminals out of the plug housing (see Anderson disassembly), and pull it down thru the hole between the motor and frame.

Removing the AC plug.

It loops up under the seat and is zip tied on in a handful of places.

There are two small bolts on the backside that are difficult to reach, so use a decent set of hex drivers with handles.

There is a fuse holder plug that connects the ground to (somewhere...).

Squeeze some tabs to get the green locking piece out.

Then squeeze more tabs to get the plug apart.

Now with the cables out, use the 3mm Allen key to loosen (but not remove) the 6 bolts on the tabs holding it up.

Remove the charger to the side (recommend the right side) by removing the 3 bolts on the side intended for removal.

On removing the last bolt, support the charger so it doesn't fall out, and carry it to the ground or elsewhere.

Remove the remaining 3 bolts using the 3mm Allen key if not installing a new charger.

Assembly

Assembly is the reverse of disassembly! Really.

Suggestion

You can extended the DC wires on the replacement Calex charger, and put the plug set sideways, and up higher to make it easier to get at.

The Charging Control Unit (CCU) on Meanwell-charger-equipped models (all 2013 and the 2014FX) collects battery temperature sensor data, battery voltage, and charger DC voltage to decide on whether to open or close the contactor. It also manages the Meanwell onboard charger which has no CANBus connection or programmability, so when the programmable Calex charger was introduced, the CCU's functions were moved to direct BMS/MBB management.

2014+ models do not have a CCU, and the BMS directly controls the contactor and onboard charger.

Location

Under the seat in front of the MBB with the connections mounted on top.

Limits

The CCU terminals are not designed for high amperage currents. Presumably, anything above the 2013's intended 30A charging limit could damage the CCU or trigger the contactor opening.

Warning:

This is always energized. Any exposure of this at any time will risk direct contact with battery terminals that could result in injury or equipment damage.

DO NOT UNCOVER this without professional-level care!

If you are in a remote location, and have trouble with a contactor unit not closing without any indication of a particular condition that interlocks it in the BMS, a little mild mechanical agitation (while the vehicle is keyed off) against the top surface with a rubber mallet might loosen it.

The Sevcon DC-DC converter is rated to IP67 for intrusion protection and seems very robust as such.

However, the connector is not sealed, faces the left side of the inside of the frame arms with not much splash protection from beneath; on 2015+ models, it is also vulnerable to debris and splash impact from the rear near the motor and belt.

No sealed connector option is currently available for Sevcon's DC-DC converter models that Zero uses.

Connector looseness could age and wear the converter prematurely due to sporadic voltage input or output changes.

Leakage across pins could cause the enable signal to activate inadvertently.

Connector Inspection

Try to inspect the pins' tabs to ensure they are in the right shape to clamp that enable pin securely.

The connector is not well-sealed, and the pins are too easy to bend into not-connecting if there's any tension/tugging on the wires.

If the connector seems grimy, remove and clean it while de-energized; then apply grease once dry before re-seating it.

Test the connector before fully re-assembling the bike.

Failure to De-energize Condition

The converter can fail in a way where it shorts its enable line and will not turn off even if the bike is keyed off.

If this condition happens in rain:

Let the bike dry out until it clears.

Attempt a dielectric grease application to the inputs while de-energized.

If the DC system output disappears:

Check DC voltage upstream of the fuse block in case the fuse block is faulty.

Check the continuity and snugness of the connectors and pins.

Check for the enable signal from the MBB

Continuity: < 1Ω between pins.

Not shorted to B+?: > 151kΩ from pin 20 to pin 7.

Not shorted to ground?: > 1MΩ from pin 20 to 18.

Protection Recommendations

Splash protection around the left-side's connector from all sides is worth considering.

Power Harness

The loopback blanking plug is a Zero electrical connector cap that wires two pins together in a loopback circuit.

This meant to emulate a basic connectivity feature for the BMS1 connection so that the vehicle's CAN Bus can operate properly.

If you own a non-longbrick X platform model or an S-platform model with a Power Tank, retain this blanking plug in case your second BMS fails to connect or issues errors that prevent your motorcycle from operating.

Firmware update refers to the process of acquiring and installing newer firmware versions from Zero onto the MBB, BMS, and the motor controller.

Dealership Updates

Firmware update for pre-2017 models must be performed by a dealership with a license with Zero and the hardware kit to connect a Windows computer to the motorcycle's data ports (OBD-II, the BMS serial port, and the Sevcon 34-pin connector).

Don't feel you have to run the bike to empty before re-charging; it's fine to charge if you've only used 10%, for example.

If you can afford extra chargers to reduce charging time, Zero's fast chargers won't hurt the batteries.

Use the bike as much as you can. If you aren't using it for a regular commute or aren't lucky enough to have the freedom to ride regularly then it will work out a lot cheaper to own a conventional motorbike.

Zero's engineers have done the work to ensure a long service life from their battery packs and have backed it up with a five year warranty with the 2014 model range onwards. That should be enough to drop any anxiety you may have and just concentrate on enjoying the bike.

The current manufacturer of cells for Zero's power packs is Farasis who are supplying pouch cells for the 2013+ model range (Gen2 and Gen3).

NMC Cell Chemistry

The chemistry used is Lithium Nickel Manganese Cobalt: LiNiMnCoO2 ("NMC" or other rearrangements of those letters).

NMC is a relatively new battery chemistry which differs from the Li-cobalt chemistry we are familiar with from mobile phone batteries and laptops.

While Li-cobalt has a higher energy density than NMC (storage capacity per kilogram), it doesn't cycle as well and ages quicker.

That's fine for a mobile phone that is likely to be obsolete after 2-3 years, but not for an electric bike.

The automotive-grade NMC cells that Farasis supply should easily satisfy the requirements of the five year warranty that Zero are providing with their current Z-Force battery packs.

It seems they should last 8-10 years if they aren't abused.

Even if you start to notice some significant deterioration after five years, the rate at which battery technology is progressing means that you should be able to buy a new battery pack with much better capacity (range) than the original for less money.

The term "monolith" refers to Zero's standard Z-Force Power Pack sealed battery assembly with specific, fixed dimensions and a single BMS with fixed communication and power interface.

A monolith is designed to package up to 4 parallel bricks, described as "4-brick" or "28s4p", referring to 4 parallel stacks of 28 cells in series.

The 4p arrangement is a "full" arrangement: the monolith is split into 4 equal quadrants each fitting a brick.

A "3-brick" arrangement was available for 2013-2016 S and DS bikes, leaving the forward upper quadrant empty (presumably filled with lightweight but load-absorbing material).

Interconnects

An interconnect wiring system electrically connects each cell across bricks that is in the same position in the series.

Interconnects minimize the complexity of cell balancing by ensuring that only 28 conductive connections are needed from the single BMS to keep cells balanced.

Interconnects also ensure that a set of 3 or 4 cells are electrically able to balance a certain amount of load, reducing stress from imbalanced load variations while running.

Interconnects do seem to embody some specialized emergency fuse safeguards.

Components and Weight

32 lb/brick ⨉ 4 brick = 128 lb

The 4-brick monolith weight of 140 lb implies 12 lb for the base plate, BMS, dog house with contactor, current sensor, fuse, and connectors.

Casing features

The front face has two holes for accessing the BMS indicators, I/O port, and reset buttons.

The front face is also removable for servicing the BMS; within, the interconnects to the cells are on the left edge (as seen while facing the battery from the front); on the top edge are connections to CANBus communications and the external power bus.

The trailing edge of the left side of the monolith casing features an arc cutout with two holes.

This cutout accommodates/mounts a CHAdeMO charging inlet (and can adapt to a Type 1 or Type 2 J1772 inlet with some fabrication).

Threaded inserts are included for the inlet mounting, sized for M5 bolts at 80mm distance from each other (center to center).

The 2017 model year shifted Zero's battery assembly to a "half monolith" or "long brick" configuration containing the same number of cells as for 2 bricks. A single BMS manages the cells in both stacks.

Model Changes

The 2017 S and DS models offer a 2p arrangement using a single long brick arranged along the forward half of the monolith frame area.

This configuration leaves the rear half of that area empty for a storage bin accessed from the side of the frame.

The prior 3p configuration is no longer for sale, but can be created by adding a Power Tank.

The long brick for this model does not have the same gapped casing that a Monolith has

So, it is less insulated from cold but dissipates heat better.

The 2017 X platform bikes are delivered by default with a non-removable long brick.

They are available optionally with single removable bricks like prior model years for an additional cost of about $500.

Design

The long brick arrangement figures suggest that each brick aligns its cells with the other brick.

Layout appears to be more efficient as a result.

Interconnects between the bricks seem to be trivial and nearly-zero-resistance, improving cell life.

There is unsupported speculation that 56s1p arrangement is a possible future evolutionary step as a result.

Zero's Battery Management System (BMS) consists of a proprietary board within the battery case to manage the cells.

2016 BMS with potting

The same board model seems to be capable and used for both single-brick (XMX Platform) bikes and power pack (SDS Platform) bikes, given software configuration changes. The board appears to be OEM-designed and has revision numbers that indicate progression over time from the 2013 model line.

Power Note

This is the one power drain on the vehicle when it is completely turned off with no charging, but it draws a very minor amount of power like a "sleep" mode.

Warning:

The board is entirely solid state and not designed for fixing, only replacement.

Any damage to this board will disable the motorcycle.

Warning:

The board has full battery voltage inputs to it at all times.

Take extreme care to avoid connections that could short, arc, or ground.

Before accessing the BMS, first turn the bike off and disconnect charging.

This ensures that the contactor is open and you do not interact with the BMS while it performs a cel balancing operation.

Location (SDS Platform / Monolith)

Behind the lower front face of the battery behind the front forks/wheel.

Remove the lower front body plastics and the front battery face to access the unit.

Location (XMX Platform / Power Tank)

Each separate brick has its own BMS inside the armored casing.

The long brick has one BMS module inside the armored casing.

Revisions

The BMS has changed layout over the years to match the monolith (particularly for long brick architecture) and increased in physical robustness and protections.

TODO identify those revisions and describe them.

Protections

The board is mounted with rubber vibration dampening.

The board is layered with a very thick coating ("dam and fill potting") to protect the components from moisture and shock damage.

It ensures that cells operate at very well-matched states of charge to ensure even load and better battery performance and overall lifetime.

Mechanism

The BMS has connections to the battery cells via the interconnect wiring and can sense cell voltage.

There are 28 contacts on the side of the back of the board (as viewed from the front of the bike looking at the battery) which connect to each cell in the "brick" series.

The BMS feeds small amounts of current to cells that are abnormally low in order to maintain battery longevity and minimize the possibility of cell damage.

It detects voltage levels on all cells, through interconnects between bricks that harness each cell in the same position in the brick's series, and through this same path able to balance cells by targeting current to the cells with the lowest voltages.

Cell balancing because of the limitations of this circuit can take a long time and is part of why Zero recommends keeping the motorcycle plugged in when unattended by default.

Schedule

Cell balancing often happens at low current levels, mainly during charge tapering when the charger is operating at the voltage limit in "constant voltage" mode.

It also can happen when the bike is long-term plugged in but turned off. The BMS may wake up and control charging specifically to balance the cells.

Precharge is a BMS pre-ride startup function to charge the main power bus before closing the contactor.

The BMS has a precharge circuit for ensuring that the contactors can close without causing damaging current spikes to the controller or other components.

Precharge is necessary because of capacitors in the controller; connecting sets of capacitors electrically requires care to match voltages because of the rate at which capacitors will charge and discharge to each other to balance potentials.

SoC is inherently an abstract / simulated measure, not one that can be directly proven with enough physical inputs.

The actual proof of state of charge is to fully discharge the battery, running an integral of current as discharged (this is the Current Method of Estimation).

But a "full" discharge must be decided from a measurement, too, taking minimum cell voltage, which sometimes (and possibly for certain cell generations) can have a single cell fall in voltage early causing SoC to drop early.

And this voltage can be a dynamic result of the rate of discharge, so that restarting the bike after a few minutes' rest period can show a higher SoC than before.

Current Integration Method, or "coulomb counting", which measures the battery current over time and estimates its integral or sum.

Battery current will reverse for regen mode and for charging, and this is measured and included in the estimation.

Voltage Method, a fairly inaccurate but simpler method where battery voltage is measured and then dynamically compensating the voltage reading by a correction term proportional to the battery current, and by using a look-up table of battery's open circuit voltage vs. temperature.

Voltage correlates to SoC well at the empty and full states, but less well in the plateau area of 20-80%.

Method Switching

The SoC method may switch during operation, and should be indicated in the event logs.

It appears to change primarily when charging starts or stops; it is probably triggered by the battery's Charge Mode state.

When the method switches, SoC may change dramatically (by 12% or more) with no clear explanation.

Temperature Effects

Batteries are chemical systems that can be very complicated to summarize.

One of the main capacity factors is the pack temperature, which is determined by both outside temperature and any heat produced internally from resistance during charging and discharging.

Temperature appears to be a significant factor in building the SoC estimation for either method.

Examples

Walk through the logic of SoC boundary parameters with some stock Zero equipment.

The 116V reported by the mobile application at 100% SoC corresponds to 4.14V (=116V/28).

0% state of charge at least naively then would correspond to 92.4V ( = 3.3V × 28).

The nominal cell voltage listed (3.65V) then corresponds to a nominal pack voltage of 102.2V, which does reflect the relatively stable battery voltage reading near the middle of the state of charge cycle in steady state.

Reframing (per Terry)

Zero will let you discharge to about 88 volts and up to 116.4 volts.

By the Farasis data sheet, this is using the full capacity of the cells with the exception of about 4 volts from the whole pack.

84 volts would be 3.0V per cell but 88 volts is pretty close.

88 volts is about 3.14V per cell and there is less than 1% energy left at 3.14V.

In any case, the state of charge calculation is driven by attempting to bracket vehicle usage to stay in this range.

The desired voltage range (to maintain battery chemistry over the stated lifetime) drives stated limits, coupled with an estimation of the amp-hours remaining from any given point in the collective state of the battery pack.

The electrolyte reacting with the active components of the cathode and anode in the cells, and releasing gas (calendar life).

The interaction between the lithium ions and the anode/cathode blend that causes a small amount of damage each time they are cycled. (Cycle life)

You just have to come to terms with the fact that from the moment the battery pack is manufactured it will very slowly lose overall capacity regardless of whether you use it or not. Li-ion batteries are good at holding their charge so you don't need to worry about letting them stand for a long time, providing they've got a reasonably good state of charge (SoC). At 40-50% SoC the overall capacity loss due to aging is minimized. At full charge the aging effects are increased but not by such a great amount that it should cause any great concern. For some owners it might be wiser to follow Zero's recommendations and just leave the bike plugged in for however long you plan to store the bike. This at least makes sure the individual cells stay balanced with each other and there's little risk of them dropping to a very low SoC at which point the aging effects begin to increase. If you let the SoC drop below their minimum threshold you run the risk of the battery pack becoming unusable. I think that's why Zero recommend leaving the bike plugged in over winter. If there's some sort of power cut mid-winter and the bike isn't checked for a few months, then at least there's a good chance the battery won't have discharged too much.

Farasis recommendations:

The manufacturer might state that you will get 500 cycles from a battery and they will be referring to full cycles. However, if you only ever use 10% of the capacity from a full charge and then top it up, you will get more cycles from it before the battery health drops to 80%. In this example you are likely to get 1500 cycles from a battery that you only ever discharge to half it's capacity. That's assuming that all other variables remain the same. In day-to-day use, variations in state of charge and temperature are more likely to affect battery life than how you cycle the battery. Taking Zero's claim's of an estimated battery pack life of 496,000 km using city ranges it would take at least 2,250 full cycles to achieve this (2014 Zero S 11.4 kWh). Taking into account the loss of capacity in this period and the figure is bound to be more like 2,500 cycles. Most trips and daily commutes will probably drop the battery to 40-50% SoC thus increasing the number of cycles we would get from the battery. Let's say we average 60 miles between charges of a 100 mile combined range over the life of the bike. Then let's allow ourselves 3,000 cycles before the battery drops to 80% health. That's still 180,000 miles. Even if we then halve that to allow for temperature and aging (very unlikely even in harsh conditions) we get a very, very conservative estimate of 90,000 miles. That should give even a heavy commuter a good five or six years of use before noticing significant reduction in range. Even then, a daily average of 60 miles would still give you a 20 mile reserve.

If you do decide to leave it at 40-50% SoC you also need to be organized enough to check the bike every couple of weeks or so. It wouldn't hurt to charge it up after a few months, leave it plugged in for a few days to make sure the cells get properly balanced, then take it for a ride to bring the SoC down to the 40-50% level again before leaving it for the next few weeks or months.

I have no doubt that the good people at Zero have done their sums, know the specifications of the batteries in detail and are confident that their battery packs will have at least 80% health after five years even if the bike is never ridden and left plugged in all the time. Zero also state in their specifications that their battery packs are good for hundreds of thousands of miles before they reach 80% of their original stated capacity. That in itself should be enough to put your mind at rest, but if it isn't then perhaps these golden rules should help:

Don't leave the bike standing empty for more than a few days.

If you have to store the bike for a long time, then either leave it plugged in and don't worry about it, or leave it at 40-50% SoC but keep an eye on it.

Just use your bike as much as you can and don't worry about the battery. The engineers have thought all this through and are backing it up with a five year warranty. The whole scene will be different in five years time, so it isn't worth thinking about.

Battery internal resistance is higher at lower temperatures, which means that while riding, losses to battery internal resistance mean a loss of range at lower temperatures.

Farasis quotes internal cell resistance as <2mΩ but it's not exactly clear how this translates into calculating those losses without some description of how that trends over temperature and charge rate.

The warmer the battery is, the lower these losses will be.

Below freezing temperatures, the battery chemistry will not allow effective charging at all, and Zero provides protections to prevent this until the battery's temperature has been raised sufficiently.

It follows that to get maximum performance, charging and discharging repeatedly at a high rate will raise cell temperature enough to reduce internal resistance so more will be delivered to the motor.

Degradation at high temperatures

Temperature is a bigger factor than state of charge when it comes to aging. Apparently, for every increase of 10F degrees in battery temperature across its lifetime, battery deterioration over that lifetime can double.

Heat Production

It is worth noting though that Li-ion batteries shouldn't generate a lot of heat when charging at normal rates.

On a Zero, charging at or below 4kW will not produce much heat.

Therefore, even if you live in a hot climate and have just been on a ride, the cells should cool down overall even while they are charging (although direct sunlight on the battery will add more heat).

You might want to be a little more careful if fast charging in a hot climate but don't forget that the BMS will either reduce the charge rate or stop charging altogether if the cell temperature exceeds the limits that the engineers have set. They have set these limits on the conservative side to avoid any claims on that five year warranty.

Storage

If you are going to store the bike, it makes sense to store it somewhere cool.

Fridge temperature is probably best but never store below freezing.

If you don't have the option of storing it somewhere cool, then don't worry about it.

A contactor is a large relay: it allows a fairly small voltage/current signal to switch a much larger voltage/current.

It has two sides:

The drive/coil side (control).

The load (contact) side.

On the drive/coil side, there's a "kickback" diode which handles the inductive spike caused when the drive to the coil ceases.

Without that diode, the energy represented in the magnetic field inside of the coil would have no place to go, so it would cause a voltage spike which can be damaging to components.

The kickback diode gives that energy somewhere to go, allowing it to ramp down fairly slowly without a big voltage spike.

Depending on how the coil side of the contactor is wound, it has a certain current requirement to pull the contactor shut, say 12V @ 100mA, which will be provided by the driving circuitry.

There's not necessarily any relationship between the coil rating and contact rating, except that bigger (higher-current rated) contacts might be heavier and require higher coil current to get the armature to move.

The kickback diode only needs to carry this amount of current, regardless of the contact side current.

If a 3A kickback diode is specified for that contactor, it will be adequate for any contact side current.

The make/break current is the rating for the contact side of the contactor.

You won't actually want to make or break the contactor under the limiting conditions (you'll always want to both make and break the contactor at exactly 0 amps), but in an emergency, it's rated to do so without the contacts welding together -- and an emergency is what the contactor is there for.

In automotive use, you often see the coil set up for 12V, drawing maybe 100mA (the current can vary widely though).

That small current pulls the contacts together, which switches on the high-current side.

Contactor Limits

Zero's effective contactor limit for the charging rate is 95% of 1C rate.

The BMS will open the contactor for the following conditions:

Inactivity

If the motorcycle is keyed off and not otherwise set in charging mode, the contactors will open after a few seconds.

If the motorcycle is keyed on and not otherwise set in charging mode, and then 30 minutes pass without control input.

Twisting the throttle is sufficient to reset this timer; otherwise restart charging once it happens.

This causes the electrolyte to become more reactive. Farasis claims to have one of the most stable electrolyte blends in the business, and use a lot of proprietary tech to keep the cathode/anode blend as least reactive as possible, but the effect is unavoidable.

High Voltage

Again, The higher the potential between the cathode and anode, the faster the reaction between the electrolyte and the actives occurs.

Very Low Voltage

Below a certain voltage (2.0-2.2V/cell) the potential between the cathode and anode is such that the battery has used all its high potential lithium, and so it starts picking on the next easiest thing, which is the copper.

This process is super ugly, as it electroplates the copper off the negative foils (anode) and electrodeposits it onto the positive foils (cathode). PERMANENT IRREVERSIBLE DAMAGE. This is super dangerous too, as the next time it is charged, that copper gets blasted back to the negative foils and lands wherever it feels like, as the anode isn't designed to deal with copper Ions. So they form big crystal sharp structures called dendrites, which at best can pierce the separator and cause high self discharge and gassing as the electrolyte nucleates (gas builds up, the cell goes to 0V and looks like a balloon) , or at worst, the dendrite is able to get a solid connection between the cathode and anode, and this causes the cell to short internally and results in fire.

Luckily for you, Zero has an amazing BMS and pack topology that sips hardly any power from the cells in a key-off state, but you still can murder the bike by approaching 0% SOC as slowly as possible until it is at its absolute lowest SOC (state of charge) and the BMS shuts the bike off. What happens is that the bike has the smallest amount of reserve battery then, and the BMS sipping away at that small amount will eventually murder the cells over a period of several years.

Battery technology is improving every year, but not at the same rate as computer technology.

A 10% per year increase in capacity might be a reasonable expectation.

We can always hope that there will be a significant breakthrough that makes is way to production and changes the state of the art much quicker.

For the time being though, we have robust technology that should give you five to ten years of service and a range of about 100 miles of mixed riding as long as you don't spend much time on fast roads.

What To Expect For Now

It's perfect for many city commuters and people who like relaxed rides taking the country roads.

You will need an ICE bike for longer journeys and touring, unless you are willing to plan in long charging stops.

If you can use your bike for your commute or have regular trips that cover less than 100 miles a day, then range anxiety won't be an issue.

Dimensions for the full Monolith are 10" width, roughly 17" height and 14" depth.

The Long Brick enclosure for 2017+ models is the same at roughly half the depth, and of course the storage area on S/DS models with this Power Pack has about the same dimensions minus clearances and dividing bracket allowances.

This is very involved, only suitable for a dealer or experienced electrical engineer equipped with a hoist, because the frame must be lifted vertically off of the battery, and the battery must be electrically detached from the systems safely.

There is also almost no realistic reason to do this for a battery under warrantee.

Steps

These are a rough sketch of the process.

Remove the belly pan and onboard charger.

Disconnect all cables leading to the battery.

Disconnect the grounding strap to the Y-shaped underseat frame piece.

Place the motorcycle on a center lift that can balance the battery on its own.

Harness the frame into a hoist and put some of the load onto that hoist.

The hoist should be rated to lift the bike's weight entirely.

(Possibly) remove the front wheel and/or forks.

(Possibly) remove the rear wheel and/or swingarm.

Use an allen key wrench to remove the 2 bolts on each side of the lower battery mount (4 total).

Use a very low overhead / right-angle H2.5 Allen key wrench from the left side of the bike ahead of the vertical frame stanchion.

Pull the board mounting plate up by enough room to fit a right-angle Allen key underneath, between the connector and the motor fins, about an inch or two.

Enable Line

The Anderson SBS-75X connector has two signaling pins which the Gen2 employs in conjunction with a feature of the Zero Quick Charger to indicate charger presence.

The feature is not completely understood, but it operates this way:

When the contactor is shut, if the enable line detects charger presence, the contactor will remain shut until or unless the enable signal is removed, or a safety limit is detected by the BMS requiring opening the contactor.

One minimal implementation joins the two pins in a simple 100kΩ resistive circuit.

Full pack voltage would supply 1mA current to such a circuit at most, so a high-current wire is not needed; just a solid circuit pinned appropriately for the connector with an inline resistor and weather+abrasion+strain-proofing).

Warning:

This implementation has not been officially vetted by Zero, and there may be unknown effects operating with such a circuit long-term

Removing the rubber boot

Only for when you are replacing the Anderson connector permanently with another type/shape of connector.

The rubber boot is held by a nylon "fir tree" plug.

Use a flat tool (screwdriver, nylon pry tool, etc) to wiggle between it and the mounting plate until loose.

After removing, you can install the rubber boot elsewhere using (for example) an M5 bolt and some washers.

The battery pack replacements performed by the manufacturer due to discovered defects wind up being upgrades to 2015 and then 2016 model year power packs, and seem to include upgraded charging circuits, so those older models will have the higher-rated fuse and work like the newer bikes, charging-wise.

Replacement

Warning:

This fuse is not meant to be user-serviceable, and could be very dangerous to replace without the exact same specification.

The fuse is downstream from the contactor, so if the contactor is open (it should be if you can't charge and the bike is keyed off), it should be de-energized.

Verify this with proper testing equipment.

It's a huge inline fuse within adhesive heat shrink, so it's difficult to extract and replace.

The wires do have ring terminals once you get the fuse out, so you could wire in a fuse breaker. Or if in a pinch just bolt them together.

Fuse Part Investigations

A 2014 SR was found to have an Eaton JJN-100 fuse, a fast-acting fuse rated for 300V and 100A.

Switchgear

Gen3 models have a fuse block but the protection has redundant upstream components in the MBB, so the fuse block just helps with isolation.

Components

Platforms

Years

Components

Rating

Notes

Photo

S,X

2013+

Accessory circuit

10A

Sumimoto plug (all years) and SAE plug (2014+ years)

2013 Fuse Block

Headlamp

10A

Instrument cluster (Dash)

running lights

5A

Turn signals (Flashers)

horn

brake lights

10A

Ignition key

5A

2015+

ABS circuit and the ignition key

5A

2015-2016 Fuse block (label inaccurate; rotated 180°)

ABS pump

25A

limited duty

ABS valve

10A

Wiring

The fuse block connects to the positive side of the DC-DC 12V Converter output on its left side.

The downstream wires enter a mesh sleeve, through a ferrite ring to clean up RF interference, and lead forward into a larger sleeve that runs (for the S-Platform) along the left side of the forward tank area.

The Kickstand has a safety cutout switch (really a sensor) to prevent motor operation while at rest.

Warning:

Kickstand Sensor Electrical Equipment Hazard

The connector is three pronged and needs to be connected correctly or can damage the MBB irreparably.

Do not disconnect or reconnect while the vehicle is keyed on or contactor is shut to be safe.

Do not short any wires together to bypass.

This is a Hall effect sensor usually containing or using sensitive measurement IC's and therefore not a simple switch.

Part

From observation, the Asahi Denso CE122 proximity sensor appears to be the part match, also used on some Triumph and KTM motorcycle models.

From the 2016 SR's sensor to its connector, the wires are Blue, Pinkish Red, and Black.

While the bike is keyed on and contactor is closed, Blue measures a stable 5V, Red measures ~2.7V and varies (need to scope this), and black appears to be a signal ground/input (needs verification when I'm not tired).

Some KTM riders with the Asahi Denso CE122 sensor have reported success using commercial bypass kits.

One such user suggested these are merely a potted 2.2kOhm resistor between the Red and Black wires (link here).

Zero motorcycles can be far more sensitive to faults on signalling pins so this should not be attempted unless you absolutely know what you are doing, and are willing to risk having to replace your MBB.

talonreaper has had luck on a 2016 SR with a 2.7kOhm resistor between the red and black kickstand sensor's wires to get home from being stranded in an emergency.

This is still not advised.

North or South pole magnetism activation? TODO

Connector

The connector appears to be a Sumimoto MT sealed series connector MT-3S-2, p/n 6180-3241.

On 2014+ models with Calex chargers, the Onboard Charger DC output cable runs along the right side of the rear face of the Monolith compartment, where it joins via Anderson SB50(?) brown connector to the charging circuit to the main pack.

Isolation Fault is jargon used on Zero Motorcycles systems to indicate a fault in some part of the system to isolate some HV electrical circuit from ground.

It can also mean the more specific condition where an attempt to locate the fault failed, an attempt to isolate the cause to a component or sub-circuit.

Indication

BMS isolation faults are indicated by a combination of codes 20, 28, and 29.

Meaning

On some part of the power system connected to the BMS at that moment, there is insufficient isolation (insulation) from ground.

This can include anything on the 116V power cabling "bus".

This is usually not a short, but can mean an imbalance that could compromise the bike's performance or safety.

If left unattended to, it could deteriorate to a serious problem; in-build protections should shut down the bike prior to damage but this itself would be unsafe happening while riding.

If the BMS reports a specific voltage in the logs with the isolation code, it means that a specific cell (the combined parallel cells at a particular level in the 28-cell series) has poor isolation to ground, roughly computable as "3.7V ⨉ N = logged voltage".

If the condition clears, check the attached equipment (chargers and cabling) for grounding isolation.

Key the bike off and on slowly, waiting after each transition to see whether the condition clears.

If the error occurs without or before the contactor is shut, then the fault is within the battery and might be due to moisture or dust entering the front of the battery faceplate where the BMS is.

If the error clears after opening the contactor, then the fault is likely downstream of the contactor, including the Accessory Charging Port signal pins, the Sevcon controller, Sevcon DC-DC 110V->12V converter, and the MBB and DC-DC connections.

Check for moisture on the Accessory Charging Port signal pins and attempt to dry them as necessary.

After everything dries out and/or the isolation fault has disappeared apply dielectric grease to all connections that would be vulnerable to water ingres (under the seat, 12V connectors, etc)

The codes are related to BMS isolation fault - as an interpretation of a voltage present relative to the frame.

A bad controller could have a single phase to the motor (M1, M2, M3 circuits) with a short to the heatsink.

Apparently Sevcon and Zero are aware of this potential problem.

The problem is apparently because the Kapton tape they use between MOSFET transistors' heatsink and the aluminum heatsink might be punctured and create intermittent low resistance contact to the controller chassis.

Warranty replacements have been reported.

Controller Isolation Diagnostic Procedure

A dealer should be able to do this easily.

Key off the bike and wait 10 minutes for the system to fully discharge.

Remove the seat.

Uncover the top of the Sevcon controller.

Verify all inputs and outputs of the Sevcon controller are de-energized (zero/low voltage).

Disconnect the cables from the controller (M1, M2, and M3, the Ampseal 34-pin connector, and B+ and B- to be extra careful) and cover the leads for safety.

Check for continuity between each phase (M1, M2, and M3 terminals) and the controller heatsink plate.

If you get continuity (low resistance reading), then controller is defective.

I got these same errors couple month ago.. problem was the SR controller bad isolation from the phase output to the aluminum plate of his body. Controller replaced and that solved the problem.. no more 20 28 and 29 error code from now. The code talk about BMS but in fact the voltage level the controller bad electrical isolation create make the BMS to think it's the battery but in my case it was not.

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